Physical activity may improve the health and quality of life of people with spinal cord injury and disease (SCI/D) by slowing or reversing physiological decline, lowering risk factors for cardiovascular disease and diabetes, improving mental health status and independence, and promoting the efficient performance of daily activities. Unfortunately, lack of access to fitness and recreation equipment is one of the primary barriers to participating in health-enhancing fitness activities for people with SCI/D, and among individuals with C5-C8 tetraplegia, access to physical activity is extremely limited. During this Phase 1 project, we will create a brake and derailleur gear-changing mechanism named Quad-Rider that enables individuals with limited hand function to safely operate a handcycle. InvoTek engineers will create four prototype Quad-Riders that enable riders with C5- C8 tetraplegia to safely propel, steer, and stop using arm, shoulder, and wrist musculature, which are still functionally intact at this level of SCI/D. Health, fitness, and recreation experts at the Lakeshor Foundation will conduct two six-week interventions, each with three persons who have tetraplegia, to assess physiological and psychosocial outcomes associated with using Quad-Rider. Our evaluation plan will: 1. ensure that the design is safe and effective for our target population, 2. ensure that participants with C5-C8 SCI/D can safely operate Quad-Rider, and 3. measure the health benefits to riders.